Data collectors are used as part of a predictive maintenance system to perform measurements on a regular basis, for example daily, weekly or monthly, of certain machine parameters, such as vibration levels, at critical points within a train of machines. Variations in the measurements of a period of time at each point can be examined for upward trends and this allows predictions to be made of the likely time of failure and hence allows the efficient planning of maintenance. Typical uses of such data collectors are in the process industries where unexpected failure of one machine can mean much lower production.
U.S. Pat. No. 4,612,620 to Davis et al describes apparatus for collecting scheduled maintenance data in accordance with a predetermined schedule. The apparatus includes a portable data collector which can be coupled to a PC. The apparatus is operable in either a data input or program mode and is coupled with a vibration transducer which is located at predetermined coded positions and data collected is stored in memory. In addition, with this system visual inspection data can be entered in the memory in the form of a numerical code along with units, designations and the like. In the data input mode of operation, the apparatus operates in conjunction with a scheduling facility which off-loads the schedule during a transfer mode into the apparatus at the commencement of any given maintenance round. The schedule serves to prompt the operator as to the sequence of data collection locations, additionally providing units, alarm threshold levels and like information. At the end of the schedule rounds, the data may be off-loaded to the processing facility. The apparatus includes logic which permits analysis of the type of transducer as the automatic carrying out of alarm level comparisons.
The hand-held instrument may be combined with a computerised predictive maintenance scheduling and data processing facility. When so combined a scheduled round of measurement procedures may be automatically transmitted to the memory of the instrument by the PC. Once this happens, the operator of the hand-held instrument receives a sequence of prompts which are read-out at the collector display as it is carried to progressive machine measurement positions. These prompts follow the predetermined maintenance schedule of the processor facility and, in the course of such activity, the operator is further provided with on-site alarm indications and the like, where appropriate. At the end of the route the data collector is again connected to the PC and the information obtained, i.e. the measurements, are uploaded to the PC. Once a"route" has been set up in the PC it will typically be used many times and be transferred to and from the data collector on every such occasion. In practice, a predetermined sequence of measurements as defined by the PC is normally followed but in special circumstances this can be deviated from. For example, if a particular machine is not working, then the measurements for that machine can be skipped, there is a facility in the Davis et al data collector to do this. It is necessary to set the information up on the PC because of the volume of measurements required and the number of units from which data is to be collected. The PC allows management of this information because in some situations there can be as many as 400 points from which data measurements are required and, consequently, the route is easily set up on the PC. In addition, during the scheduled round of a plant additional measuring points can be included which can be uploaded with the route measurements. These additional measurements are termed "off-tour" measurements.
The whole thrust of the aforementioned Davis et al patent is towards providing the operator with a predetermined maintenance schedule so that the operator follows the schedule as downloaded to the hand-held unit and takes measurements of each machine in turn.